The Frozen Heart
by ZackFairLover
Summary: Alone. Isolated. Gifted with powers over snow - powers that instill fear in others. Two beings exist in this lonely fashion, until a chance string of music brings them together. What happens next? Romance and world domination ensue. Frozen/World of Warcraft crossover - Elsa and the Lich King.
1. Prologue

Elsa stood in her newly built ice palace, panting heavily from her exertion. The last words of her heartfelt song reverberated through the halls, making the ice shiver with the words. Unbeknownst to the snow queen, her song had traveled further than her castle. It echoed through the surrounding mountains; the distance it traveled made the words sound more eerie and haunting. Through the raging snow storm it carried, arriving at last at a very different castle.

Through black-blue stone walls of bleak stone the song carried, bouncing off of walls lit by the sickly glow of ice. It passed through banshees and spirits, dodged ghouls and geists, and made death knights sneer in disgust at its innocent tone. The abominations, on the other hand, giggled at the words of the song.

Unlikely though it seemed, the song managed to reach a throne of ice situated at the top of the citadel - carried, perhaps, by a magic greater than frost or death. Its haunting tune pierced the ears of an armored figure who sat brooding upon the frozen throne. Startled, the man - if he could still be called such - cocked his head to listen. At first the melody made his lips curl in revulsion, but as he listened to them the man began to slowly nod.

Beneath the citadel, deep in the bowels of the earth, a frozen heart began to thaw. It was not much - but it was a start.


	2. Chapter 1

The song was pushed out of the Lich King's mind for a time as he attended to more important business. The Argent Crusade had set up camp in Icecrown, as had the traitorous Knights of the Ebon Blade. Arthas had no doubts that his undead army would crush them - but still, their presence required his attention.

Shouts from within his citadel distracted the king from his battle plans. Irritated, he rose up from his throne, ice cracking upon his armor as he moved. Frost gathered around the Lich King as he strode ponderously towards the disturbance.

Eventually he found the source of his annoyance. A trio of abominations stood before Blood Prince Keleseth, looking sheepish as he yelled at them. Arthas quirked a snowy eyebrow, curious despite his annoyance, and waited for the San'layn to notice him.

He wasn't sure what tipped his lieutenant off to his presence - was it the freezing cold that accompanied him into the room, or the beaming faces of the abominations as they spotted their beloved master? Whatever the case, Keleseth stopped mid-rant and turned, bowing low before the Lich King.

"Master, forgive this disturbance," he said in a cloying, obsequious tone. "I was simply disciplining these oafs for an unforgivable offense. I did not intend for the matter to reach your ears- "

Arthas cut him off with a wave of his plate covered hand. "What, exactly, did they do?" he asked. His voice was hollow, like the howling winds of a snow storm, and it chilled the Blood Prince to the bone.

"They were...singing, my lord." The vampire elf was obviously disgusted.

The Lich King, however, was curious. He had always had a soft spot for the abominations. They were simple creatures, but fiercely loyal to him; besides that, they were one of a very few groups of beings that seemed truly glad whenever they saw him.

Arthas turned to the abominations, his face speculative. The trio were torn between smiling at their maker and looking ashamed of their actions. Their hideous faces were enormously expressive, and they wore their emotions honestly. Surrounded as he was by lieutenants that masked their feelings and used deceit in an attempt to manipulate him, the Lich King found the change refreshing.

As he looked at the abominations, Arthas found himself becoming curious. They were _very_ simple creatures - the fact that they remembered a song surprised him. "Sing to me," the Lich King commanded, relishing the look of horror on Prince Keleseth's face.

The abominations immediately broke into a horrendous cacophony of noise. Each seemed to have started at a different point in the song, and none of them seemed to know the words very well. They hummed what they did not know, their exposed guts vibrating as they did so. The Lich King found himself fighting a smile. It was obvious that Keleseth wanted to leave, but he didn't dare interrupt to ask Arthas' leave to go. As such, he was forced to stay - and listen to the "music".

Much to his surprise, Arthas realized that he recognized the tune. The realization came to him after one of the abominations, his three arms waving off-time from the music - all three versions of it, impressively - growled " _Let it go_ ," in a wavery, gravelly voice. Shocked, Arthas raised a plated hand for them to stop singing.

It took a moment. One of the abominations had been shyly watching his master, and stopped straight away. Another was attempting to dance, and it was a few seconds before its bloated body swiveled around and saw Arthas' raised, frost coated hand. The third abomination proved more difficult to halt. Its eyes were closed as it hummed with reckless abandon, its intestines and dangling eyeball quivering with the fervor of its efforts. Arthas watched, amused, as the other two "surreptitiously" attempted to make it stop - which involved much obvious kicking and grunting that the abominations clearly thought was subtle.

Eventually the abomination took the hint, stopping in the middle of belting out a verse. As soon as it was quiet (after the saronite fortress had finished distorting and echoing the sound), the Lich King spoke. "Where did you hear that?"

The abominations looked at one another, shrugging - which looked interesting with three arms - and grunting. "Dunno," said one. "Him," said another, pointing at the first. It was the third answer that caught the Lich King's interest. "Da walls," the final abomination mumbled.

Arthas nodded slowly. Sounds carried well in this place - he was sure that most of the castle had heard the abominations' performance. "And you remember the song?" he asked, still surprised that three of his simple-minded servants had managed to retain the tune.

They shrugged again. "Is catchy," one said, and the others nodded their agreement.

Arthas fought a smile, not wanting Keleseth to see such an emotion from him. "Very well. Dismissed."

Prince Keleseth turned to him as the abominations shuffled happily out of the room. "But, Master - shouldn't we punish them?"

Arthas allowed himself a small smirk as he clapped Keleseth's shoulder, the cloth where his hand touched freezing upon contact. As he strode out of the room, the Lich King called back, "Let it go."


	3. Chapter 2

It was a _very_ catchy tune.

Arthas frowned from atop his throne. He had important things to be concerned with, but he couldn't seem to get the blasted song out of his head! It had been stuck in his mind for days without reprieve. To make matters worse, the Lich King didn't know all of the lines - only the tune, stuck on never-ending repeat in his head.

All of the abominations had learned the song and were humming it now. Even a few of the geists had picked up the habit. Since the lower level servants in the Citadel were constantly being rotated out with those from the front line, the song had spread throughout all of Icecrown. The higher ranking undead, at first annoyed by the song, now reported with malevolent glee that it was terrifying the Argent Crusade. Arthas' favorite report was of an abomination who had ploughed through a squad of paladins, all while humming vigorously. Let the survivors report _that_ back to Fordring, he thought with malicious amusement. He was sure the older man wouldn't know what to think.

The panic the song was causing amongst the Lich King's enemies was well worth the minor annoyance of having it stuck in his head. Still, Arthas thought that the abominations had it easy. They were free to sing the song to their heart(s)'s content, to get it out of their little minds. If Arthas were to start singing, or even quietly humming, he was sure there would be consequences. His council would think he had lost his mind - and Arthas could not afford to lose their support, not with his forces threatened on all fronts.

...

After a week without relief, the Lich King was almost to the point of not caring what the council though. He _had_ to get the song out of his head! Without knowing the words, his mind had begun to fill in the blanks with his own lines. It was driving the Lich King mad.

Still, he was determined to be subtle. At the end of a meeting, the Lich King told his advisors that he intended to survey his forces. He turned down all offers of accompaniment, and sent everyone off on tasks to make sure they were kept occupied during his absence. It wouldn't do for one of them to decide to check in on their master in their spare time...

That task taken care of, Arthas took the transporter to his frozen throne. After a moment's consideration, he let out a sharp, summoning whistle. Though he could easily open portals of frost to travel across Northrend, Arthas wanted to conserve his power. The forces of the living were proving to be more resilient than he had thought, and the Lich King was determined to use all of his power to stop them.

Besides, he thought with a rare smile, this way he got to see an old friend.

A hollow whinny alerted him to Invincible's approach, and Arthas turned to greet his oldest and most loyal friend. Glowing eyes looked at him with adorations as he stroked his mount's nose. The undead horse seemed unbothered by the frost that clung to his master; when Arthas mounted him, the horse made no sound of complaint at the weight of the Lich King's armor.

The smile remained on Arthas' face as they took off. It was very rare for him to ride Invincible now; he had missed it.

True to his word, Arthas surveyed his forces from the air. The grin he wore disappeared as he did so. Matters were more dire than he had thought: the factions that fought against him had gained ground.

Troubled by this, Arthas turned Invincible mid-air to head back Icecrown Citadel - but the song suddenly resurfaced in his mind with a vengeance. Reminded of the original purpose of his trip, Arthas let out a frosty curse and turned Invincible once more, this time towards the Storm Peaks.

It took a while to find a spot that fit his needs, but Arthas eventually let Invincible land on a mountain top. It was some distance from the grounds of the Argent Tournament, on the border of Icecrown and the Storm Peaks. The distance was good, as was the storm that raged upon the mountain - it ought to swallow his voice and keep anyone from hearing what the Lich King was about to do.

With a deep breath Arthas dismounted, patting Invincible as he did so. He drew Frostmourne and plunged it into the snow, keeping one hand upon its hilt. The empty spot in his chest leapt at what he was about to do. Unsure of the original words, Arthas gave voice to those his mind had assigned to the tune:

My eyes glow blue in their sockets tonight

So inhuman - can't you see?

A kingdom of death and mayhem

And I've made myself its King

Frostmourne is howling with the souls locked up inside

Invincible, upon him I'll ride


	4. Chapter 3

The wind kept Elsa company within her frosty palace. It sang to her, and she ahd made a habit of listening to it on the balcony each night. Her newfound freedom was still exhilarating, but there was little for her to do, save to test the limits of her power.

So, during the day Elsa crafted furnishings for her new home and raised minions from the snow and ice. Though fun and loyal, they were unable to speak, and so did nothing to keep her company. By the time night fell, the loneliness was unbearable - and so Elsa went out onto her balcony and listened to the whispers the wind brought her.

But tonight...tonight was different.

At first she heard nothing, but then a powerful gust began to pick up. Upon it, Elsa heard a familiar strain of music - one that she herself had given life to.

Fascinated, the snow queen used her magic to give the wind strength. She listened to the unfamiliar words it brought to her and sensed in them a kindred spirit - someone just as lonely and misunderstood as she; someone with a frozen heart.

The song reached its climactic ending, capturing Elsa's heart as the harsh voice cried out:

Let the dead rise u-u-up! -

Undeath never bothered me anyway.

Elsa listened to the silence that followed, for some reason breathless. Then, to her surprise, the song began again. It seemed the mysterious stranger needed to get the words out. The snow queen listened in silence for a moment - then, her heart pounding, she sang back to the unknown voice with the original words of the song. Their words wove together at the same time as their hearts, a strange duet of ice and death. A common link of loneliness, of powers misunderstood and feared, bonded the duo.

Elsa's heart continued to pound long after the song had ended. Here, she knew, was someone who would understand her. Here was one with whom she could be herself.

A strange sensation filled the Lich King's empty chest as he stood atop his lonely mountain. The lilting voice that had joined his echoed around him, given life by the storm.

Arthas stood there in silence, listening to the faint remnants of their duet, until Invincible nudged his shoulder curiously. Arthas reached back and soothed his friend by stroking his nose. Then he withdrew Frostmourne from the ground with a shower of snow. Sheathing it, Arthas turned and mounted Invincible.

"I'm going to find that woman," the Lich King swore.

...

Beneath the citadel, the ice upon the frozen heart had begun to crack. A golden-haired little boy watched it - and smiled.


End file.
